// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ipc/message_filter_router.h"

#include <stddef.h>
#include <stdint.h>

#include "base/macros.h"
#include "ipc/ipc_message_macros.h"
#include "ipc/ipc_message_utils.h"
#include "ipc/message_filter.h"

namespace IPC {

namespace {

    bool TryFiltersImpl(MessageFilterRouter::MessageFilters& filters,
        const IPC::Message& message)
    {
        for (size_t i = 0; i < filters.size(); ++i) {
            if (filters[i]->OnMessageReceived(message)) {
                return true;
            }
        }
        return false;
    }

    bool RemoveFilterImpl(MessageFilterRouter::MessageFilters& filters,
        MessageFilter* filter)
    {
        MessageFilterRouter::MessageFilters::iterator it = std::remove(filters.begin(), filters.end(), filter);
        if (it == filters.end())
            return false;

        filters.erase(it, filters.end());
        return true;
    }

    bool ValidMessageClass(int message_class)
    {
        return message_class >= 0 && message_class < LastIPCMsgStart;
    }

} // namespace

MessageFilterRouter::MessageFilterRouter() { }
MessageFilterRouter::~MessageFilterRouter() { }

void MessageFilterRouter::AddFilter(MessageFilter* filter)
{
    // Determine if the filter should be applied to all messages, or only
    // messages of a certain class.
    std::vector<uint32_t> supported_message_classes;
    if (filter->GetSupportedMessageClasses(&supported_message_classes)) {
        DCHECK(!supported_message_classes.empty());
        for (size_t i = 0; i < supported_message_classes.size(); ++i) {
            const int message_class = supported_message_classes[i];
            DCHECK(ValidMessageClass(message_class));
            // Safely ignore repeated subscriptions to a given message class for the
            // current filter being added.
            if (!message_class_filters_[message_class].empty() && message_class_filters_[message_class].back() == filter) {
                continue;
            }
            message_class_filters_[message_class].push_back(filter);
        }
    } else {
        global_filters_.push_back(filter);
    }
}

void MessageFilterRouter::RemoveFilter(MessageFilter* filter)
{
    if (RemoveFilterImpl(global_filters_, filter))
        return;

    for (size_t i = 0; i < arraysize(message_class_filters_); ++i)
        RemoveFilterImpl(message_class_filters_[i], filter);
}

bool MessageFilterRouter::TryFilters(const Message& message)
{
    if (TryFiltersImpl(global_filters_, message))
        return true;

    const int message_class = IPC_MESSAGE_CLASS(message);
    if (!ValidMessageClass(message_class))
        return false;

    return TryFiltersImpl(message_class_filters_[message_class], message);
}

void MessageFilterRouter::Clear()
{
    global_filters_.clear();
    for (size_t i = 0; i < arraysize(message_class_filters_); ++i)
        message_class_filters_[i].clear();
}

} // namespace IPC
